Since others already suggested mostly on-topic suggests, here's an alternative suggestion:
Instead of looking specifically for a mentor - look for an open source project that you can help with. Ideally one with a discord or something to it's easy to be in contact the the lead dev. A lot people don't mind mentoring juniors, but in my experience it doesn't happens that explicitly - "be my mentor" - and it might sound like you're asking them a lot.
If you invert it into "Hey I wanna help you with your open-source project, but I don't really know what to do, what your expectations are, how to implement a specific feature" - then you're offering to do work them, instead of asking for something. And implicitly you'll get mentorship in return.
And "real" projects probably also look better on your github / portfolio than only some dummy projects for learning purposes
Because Wordpress is also hosting 1000s of plugins that WP engine users can install.
I'm not sure what the license regarding those things is, WP engine could probably just mirror it -
But they basically got locked out of the default ecosystem infrastructure.